Phonological Reduction in Swedish

In this paper, the importance of pronunciation variation modelling is discussed. As a first step in developing a model of Swedish pronunciation variation due to speaking style and speech rate, a tentative reduction rule system has been developed. An assessment experiment testing the impact of phonological reduction, as defined by this system, on the perceived naturalness of speech synthesis was conducted. Canonical and reduced synthetic speech stimuli with three different speech rates were presented to näıve subjects. The reduced pronunciations were significantly more often perceived as more natural than the canonical pronunciations at the higher speech rates, while there was no significant general difference in perceived naturalness depending on reduction level for the lowest rate. The dependence on speech rate for perceived naturalness was significant. A possible cause for some observed differences in perceived naturalness depending on the nature of specific stimuli is discussed.